U.S. patent number 3,933,134 [Application Number 05/405,483] was granted by the patent office on 1976-01-20 for method and apparatus using proportional residual gas storage to reduce no.sub.x emissions from internal combustion engines.
This patent grant is currently assigned to Honda Giken Kogyo Kabushiki Kaisha. Invention is credited to Kazuo Inoue, Shizuo Yagi.
United States Patent |
3,933,134 |
Yagi , et al. |
January 20, 1976 |
Method and apparatus using proportional residual gas storage to
reduce NO.sub.x emissions from internal combustion engines
Abstract
Reduction of NO.sub.x emissions from a four-cycle stratified
charge internal combustion piston engine is accomplished by (a)
spark ignition of a rich mixture in a first chamber containing
residual exhaust gas, followed by (b) torch ignition of rich
mixture in a second chamber under turbulent conditions, causing (c)
torch ignition of a stratified charge in a lean mixture in the main
combustion chamber. The result is a reduction in peak temperature
in the combustion process, with consequent reduction in NO.sub.x
emissions in the engine exhaust gases. Exhaust gas is not
recirculated. Said first chamber, which contains residual gas from
the previous combustion cycle, contains the spark gap between spark
plug electrodes and the spark gap is located near a restricted
connection between the first and second chambers and remote from a
closed end of the first chamber. Means are provided for changing
the volume of said first chamber while the engine is operating, in
accordance with variations in load on the engine.
Inventors: |
Yagi; Shizuo (Asaka,
JA), Inoue; Kazuo (Ianashi, JA) |
Assignee: |
Honda Giken Kogyo Kabushiki
Kaisha (Tokyo, JA)
|
Family
ID: |
23603883 |
Appl.
No.: |
05/405,483 |
Filed: |
October 11, 1973 |
Current U.S.
Class: |
123/259; 123/295;
123/260 |
Current CPC
Class: |
F02B
19/1014 (20130101); F02B 19/1061 (20130101); Y02T
10/125 (20130101); Y02T 10/12 (20130101); F02B
1/04 (20130101) |
Current International
Class: |
F02B
19/10 (20060101); F02B 19/00 (20060101); F02B
1/00 (20060101); F02B 1/04 (20060101); F02B
019/10 (); F02B 019/16 () |
Field of
Search: |
;123/32ST,32SP,32SA,191S,191SP,75B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Burns; Wendell E.
Assistant Examiner: Cox; Ronald B.
Attorney, Agent or Firm: Lyon and Lyon
Claims
We claim:
1. In a four-cycle spark-ignition internal combustion reciprocating
piston engine having a main combustion chamber with a valved intake
passage for a lean mixture, an auxiliary combustion chamber having
a valved intake passage for a rich mixture, and a torch nozzle
restriction connecting said chambers, the improvement for
minimizing NO.sub.x in the engine exhaust gases comprising, in
combination: a residual gas chamber having a restricted opening at
one end communicating with the auxiliary chamber and having an end
wall remote from said opening, a spark plug having electrodes
forming a spark gap positioned in said residual gas chamber nearer
to the restricted opening than to said end wall, the position of
said restricted opening with respect to the auxiliary chamber being
such that the suction stroke of the piston serving to draw a rich
mixture into and through the auxiliary chamber and through the
torch nozzle restriction into the main chamber does not
substantially change the contents of the residual gas chamber which
comprise residual burned gas from the previous combustion cycle of
the engine, the restricted opening serving to promote mixing of
rich mixture and residual gas in said residual gas chamber during
the compression stroke of the piston, whereby at the time of
ignition, the concentration of residual gas near said end wall of
said residual gas chamber is greater than in the region containing
said spark gap.
2. The combination set forth in claim 1 in which the axis of the
torch nozzle restriction is misaligned with respect to the axis of
said restricted opening.
3. The combination set forth in claim 1 in which the auxiliary
chamber is formed within a thin wall metal cup of low heat
capacity, the cup having a first aperture forming the torch nozzle
restriction and a second aperture forming said restricted
opening.
4. The combination set forth in claim 1 in which the auxiliary
chamber is formed within a thin wall metal cup of low heat
capacity, the cup having a cylindrical portion closed by a curved
bottom portion, the cup having a first aperture in both portions
forming the torch nozzle restriction, the cup having a second
aperture in the cylindrical portion at right angles thereto forming
said restricted opening.
5. The combination set forth in claim 1 in which said residual gas
chamber is substantially cylindrical and extends at substantially
right angles from a wall of said auxiliary chamber.
6. In a four-cycle spark-ignition internal combustion reciprocating
piston engine having a main combustion chamber with a valved intake
passage for a lean mixture, an auxiliary combustion chamber with a
valved intake passage for a rich mixture, and a torch nozzle
connecting said chambers, the improvement for minimizing NO.sub.x
in the engine exhaust gases comprising, in combination: a residual
gas chamber having a restricted opening communicating with the
auxiliary chamber and having an end wall remote from said opening,
a spark plug having electrodes forming a spark gap positioned in
said residual gas chamber, the volumes of the chambers being
related as follows: ##EQU2## where: V.sub.a = volume of auxiliary
chamber
V.sub.rg = volume of residual gas chamber
V.sub.m = volume of main chamber at top dead center.
7. In a four-cycle spark-ignition internal combustion reciprocating
piston engine having a main combustion chamber with a valved intake
passage for a lean mixture, an auxiliary combustion chamber with a
valved intake passage for a rich mixture, and a torch nozzle
connecting said chambers, the improvement for minimizing NO.sub.x
in the engine exhaust gases comprising, in combination: a residual
gas chamber having a restricted opening communicating with the
auxiliary chamber and having an end wall remote from said opening,
a spark plug having electrodes forming a spark gap positioned in
said residual gas chamber, the volumes of the auxiliary chamber and
the residual gas chamber being related as follows: ##EQU3## where:
V.sub.a = volume of auxiliary chamber
V.sub.rg = volume of residual gas chamber.
8. In a four-cycle spark-ignition internal combustion reciprocating
piston engine having a main combustion chamber with a valved intake
passage for a lean mixture, an auxiliary combustion chamber with a
valved intake passage for a rich mixture, and a torch nozzle
connecting said chambers, the improvement for minimizing NO.sub.x
in the engine exhaust gases comprising, in combination: a residual
gas chamber having a restricted opening communicating with the
auxiliary chamber and having an end wall remote from said opening,
a spark plug having electrodes forming a spark gap positioned in
said residual gas chamber, the cross section area of the torch
nozzle being related to the volumes of the residual gas chamber and
auxiliary chamber as follows: ##EQU4## where: F.sub.t = area of
torch nozzle
V.sub.rg = volume of residual gas chamber
V.sub.a = volume of auxiliary chamber.
9. In a four-cycle spark-ignition internal combustion reciprocating
piston engine having a main combustion chamber with a valved intake
passage for a lean mixture, an auxiliary combustion chamber with a
valved intake passage for a rich mixture, and a torch nozzle
connecting said chambers, the improvement for minimizing NO.sub.x
in the engine exhaust gases comprising, in combination: a residual
gas chamber having a restricted opening communicating with the
auxiliary chamber and having an end wall remote from said opening,
a spark plug having electrodes forming a spark gap positioned in
said residual gas chamber, the area of the restricted opening as
compared to the volume of the residual gas chamber being as
follows; ##EQU5## where; F.sub.rg = area of restricted opening
V.sub.rg = volume of residual gas chamber.
10. The combination set forth in claim 1 in which the spark plug
electrodes are elongated to extend through at least a portion of
the residual gas chamber.
11. The combination set forth in claim 1 in which said residual gas
chamber is formed in a sleeve connected by threads at one end to
the engine, and connected by threads at the other end to the spark
plug, the spark plug electrodes being extended to position the
spark gap near said restricted opening.
12. The combination set forth in claim 1 in which the residual gas
chamber is formed within a thin wall liner of low heat capacity,
the liner having an opening to receive the spark plug
electrodes.
13. The combination set forth in claim 1 in which means are
provided for varying the volume of the residual gas chamber.
14. In a four-cycle spark-ignition internal combustion
reciprocating piston engine having a main combustion chamber with a
valved intake passage for a lean mixture, an auxiliary combustion
chamber with a valved intake passage for a rich mixture, and a
torch nozzle connecting said chambers, the improvement for
minimizing NO.sub.x in the engine exhaust gases comprising, in
combination: a residual gas chamber having a restricted opening
communicating with the auxiliary chamber and having an end wall
remote from said opening, a spark plug having electrodes forming a
spark gap positioned in said residual gas chamber, means for
varying the volume of the residual gas chamber, said means
including a plug slidably mounted within the residual gas chamber
to define the end wall thereof, and means for moving said plug in
accordance with engine operating conditions.
15. In a four-cycle spark-ignition internal combustion
reciprocating piston engine, the combination of: a main combustion
chamber with an intake passage for a lean mixture, an auxiliary
combustion chamber having an intake passage for a rich mixture, a
torch nozzle restriction connecting said chambers, mechanically
operated valves movable in timed sequence for controlling flow
through said intake passages, a residual gas chamber having a
restricted opening at one end communicating with the auxiliary
chamber and having an end wall remote from said opening, a spark
plug having electrodes forming a spark gap positioned in said
residual gas chamber nearer to the restricted opening than to said
end wall, the position of said restricted opening with respect to
the auxiliary chamber being such that the suction stroke of the
piston serving to draw a rich mixture into and through the
auxiliary chamber and through the torch nozzle restriction into the
main chamber does not substantially change the contents of the
residual gas chamber which comprise residual burned gas from the
previous combustion cycle of the engine, the restricted opening
serving to promote mixing of rich mixture and residual gas in said
residual gas chamber during the compression stroke of the piston,
whereby at the time of ignition, the concentration of residual gas
near said end wall of said residual gas chamber is greater than in
the region containing said spark gap.
16. For use with a four-cylinder spark-ignition internal combustion
reciprocating engine having an auxiliary combustion chamber
connected through a torch nozzle with a main combustion chamber,
the improvement comprising: means forming a residual gas chamber
having a restricted opening at one end, means for securing said gas
chamber to the engine to establish communication with the auxiliary
chamber through said restricted opening, said chamber having a wall
remote from said opening, means on said chamber for connection with
a spark plug so that the spark gap defined by the spark plug
electrodes is positioned within the residual gas chamber nearer to
the restricted opening than to said wall, the position of said
restricted opening with respect to the auxiliary chamber being such
that the suction stroke of the piston serving to draw a rich
mixture into and through the auxiliary chamber and through the
torch nozzle restriction into the main chamber does not
substantially change the contents of the residual gas chamber which
comprise residual burned gas from the previous combustion cycle of
the engine, the restricted opening serving to promote mixing of
rich mixture and residual gas in said residual gas chamber during
the compression stroke of the piston, whereby at the time of
ignition, the concentration of residual gas near said wall of said
residual gas chamber is greater than in the region containing said
spark gap.
17. In a four-cycle spark-ignition internal combustion
reciprocating piston engine for minimizing emissions of NO.sub.x in
the engine exhaust gases, the combination of: a main combustion
chamber having a valved intake passage for a lean mixture, an
auxiliary combustion chamber having a valved intake passage for a
rich mixture, means forming a torch nozzle restriction connecting
said chambers, means forming a residual gas chamber having a
restricted opening at one end communicating with said auxiliary
chamber, and having an end wall remote from the restricted opening,
the total volume of the auxiliary chamber and residual gas chamber
being from 5 to 30% of the total combined volume of all three
chambers, the suction stroke of the piston serving to draw a lean
mixture into the main chamber and a rich mixture into and through
the auxiliary chamber and torch nozzle restriction into the main
chamber without materially affecting the contents of the residual
gas chamber, the shape of the residual gas chamber and the position
of the restricted opening acting to promote mixing so that after
the compression stroke of the piston the concentration of residual
gas from the previous combustion cycle of the engine mixed with
rich mixture is greater near said end wall of the residual gas
chamber than near said restricted opening, sparking means in said
residual gas chamber positioned nearer to said restricted opening
than to said end wall for igniting the mixture therein whereby a
first flame is caused to extend through the restricted opening to
produce turbulent ignition in the auxiliary chamber, thereby
causing a second flame to extend through the torch nozzle
restriction and into the main chamber.
18. The method of operating a four-cycle spark-ignition internal
combustion reciprocating engine for minimizing emissions of
NO.sub.x in the engine exhaust gases, the engine having a main
chamber and an auxiliary chamber connected by a torch nozzle, one
wall of the main chamber being formed by a piston, comprising the
following steps: retaining in an ignition chamber a quantity of
residual gas from the previous combustion cycle of the engine,
inducting a lean air-fuel mixture into a main combustion chamber,
simultaneously inducting a rich air-fuel mixture into the auxiliary
chamber and a portion thereof through the torch nozzle into the
main chamber, all without substantial change in the residual gas in
the ignition chamber, the overall air-fuel ratio being leaner than
stoichiometric, compressing the mixtures, mixing the residual gas
during compression with a quantity of rich mixture from the
auxiliary chamber, spark igniting the compressed mixture in the
ignition chamber adjacent a restriction to send a flame through the
restriction into the auxiliary chamber to ignite the contents
thereof and thereby cause a flame to propagate through the torch
nozzle into the main chamber.
19. The combination as set forth in claim 15 in which throttle
valves are positioned upstream from the said intake valves in each
of said intake passages.
Description
This invention relates to internal combustion engines of the spark
ignition piston type and is particularly directed to improvements
over the three-valve stratified-charge engine disclosed in the
copending application of Date et al. Ser. No. 353,786 filed Apr.
23, 1973. The device and method of the present invention relate to
an engine of this type in which a lean mixture is delivered to the
main combustion chambers and a rich mixture is delivered to
auxiliary combustion chambers. Each auxiliary chamber is connected
to its respective main chamber through a restricted torch nozzle.
The overall air-fuel ratio is leaner than stoichiometric so that
excess oxygen is present in the exhaust gases.
The principal object of the present invention is to provide further
reduction of oxides of nitrogen (referred to as NO.sub.x) in the
exhaust gases discharged into the atmosphere. The present invention
enables the NO.sub.x emissions level to be lowered while at the
same time avoiding any increase in carbon monoxide (CO) or unburned
hydrocarbon (HC) emissions.
Conventional automobile engines presently being manufactured
commonly recirculate considerable quantities of exhaust gas mixed
with the incoming combustible mixture of fuel and air. However,
such conventional recirculation of exhaust gas reduces the
efficiency of the engine, and under variable operating conditions
encountered by automobile engines an increase in emissions of CO
and HC is brought about by such recirculation. Also, it is well
known that "drivability" suffers when recirculation of exhaust gas
is employed. Moreover, the recirculation manifold is subject to
objectionable accumulation of carbon.
It is a feature of the present invention that residual exhaust gas
is mixed with the rich mixture from each auxiliary chamber to
reduce NO.sub.x generation, but without increasing the total
residual gas volume. No complicated installation is required to
recirculate exhaust gas, but the beneficial effect of reducing
NO.sub.x is obtained.
In accordance with the present invention, a residual gas chamber is
employed in addition to each auxiliary chamber. This residual gas
chamber is located and positioned so that it has a restricted
opening at one end communicating with the auxiliary chamber which
receives the rich mixture by way of the "third" valve. The spark
gap between the plug electrodes is positioned in this residual gas
chamber at a location near the restricted opening. This
comparatively simple structure and the method of operation reduce
the production of NO.sub.x to a surprising degree, without any
noticeable side effects or secondary phenomenon adversely affecting
performance of the engine. Exhaust gases are not recirculated, but
residual gases remaining in the residual gas chamber at the end of
the exhaust stroke are employed to reduce NO.sub.x.
In the general plan of operation, residual exhaust gases remain in
the main combustion chamber, the auxiliary chamber and in the
residual gas chamber at the end of the exhaust stroke of the
piston. During the subsequent intake stroke of the piston, the main
intake valve opens to admit a lean mixture into the main combustion
chamber, and the auxiliary or "third" valve opens to admit rich
mixture into the auxiliary chamber. The exhaust valve in the main
chamber closes. During the course of the intake stroke the quantity
of residual gas in the residual gas chamber remains substantially
unchanged, but rich mixture fills the auxiliary chamber and is
drawn through the torch nozzle into the main chamber where it forms
a region of relatively rich mixture encompassed within a larger
region of relatively lean mixture. Some residual exhaust gases are
dispersed in the main chamber. During the following compression
stroke of the piston, the exhaust valve, the main inlet valve, and
the auxiliary valve are closed and the increase in pressure in the
main chamber causes reverse flow through the torch nozzle so that
the mixture in the auxiliary chamber is leaner than when initially
inducted, and so that the residual gas chamber containing the spark
gap between the spark plug electrodes then contains a compressed
mixture of air, fuel and residual gases.
At the end of each compression stroke, the total amount of residual
gas in all three chambers is constant. However, the amount of
residual gas in the residual gas chamber is proportional to the
amount of fresh charge in that chamber. An ignitable fresh mixture
exists around the spark gap near the restricted opening and remote
from the end wall.
Near the end of the compression stroke, this mixture in the
residual gas chamber is ignited by the spark plug electrodes, and
the peak temperature of the burning mixture is lower than it would
be if the residual exhaust gases were not present. The increase in
pressure and temperature of the burning gases causes a first torch
or flame jet to extend through the restricted opening to ignite the
rich mixture in the auxiliary chamber. This burning mixture then
projects a torch flame through the torch nozzle into the main
combustion chamber to initiate burning in the relatively rich
region and thereby ignite the larger volume of relatively lean
mixture within the main combustion chamber. The peak temperatures
generated in the spark plug chamber and auxiliary chamber are lower
than the peak temperature which would have been generated if no
separate spark plug chamber containing residual gas were employed.
The turbulent mixture in the auxiliary chamber includes burned gas
from the residual gas chamber, thus lowering the peak
temperature.
Also, better combustion in the main combustion chamber is achieved
because of the smaller amount of residual gas remaining in the main
chamber at the time of ignition.
Burning of the lean mixture in the main combustion chamber
continues throughout the power stroke. Only the main chamber has an
exhaust valve and it is open during the exhaust stroke to allow the
exhaust gases to leave the engine. As set forth in the copending
application referred to above, the exhaust gases continue to burn
in the exhaust system downstream from the exhaust valve in order
that the excess air may continue to burn any unburned hydrocarbons
(HC) and in order that carbon monoxide (CO) may be oxidized to
carbon dioxide (CO.sub.2) before discharge into the atmosphere.
It is also a feature of the method and apparatus of this invention
to provide means for varying the volume of the residual gas
chamber, so that the volume may change in a desired manner as the
load on the engine changes.
Other and more detailed objects and advantages will appear
hereinafter.
In the drawings,
FIG. 1 is a sectional elevation partly broken away showing a
preferred embodiment of this invention.
FIG. 2 is a view similar to FIG. 1 showing a first modification,
employing a spark plug with long electrodes.
FIG. 3 is a view similar to FIG. 1 showing a second modification,
employing a liner within the residual gas chamber.
FIG. 4 is a sectional elevation showing a third modification which
includes apparatus for changing the volume of the chamber which
contains the spark plug electrodes, the chamber being adjusted to
minimum size.
FIG. 5 is a sectional detail taken substantially on the lines 5--5
as shown in FIG. 4.
FIG. 6 is a view similar to FIG. 4, the spark plug chamber being
adjusted to maximum size.
FIG. 7 is an end view taken in the direction 7--7 as shown in FIG.
4.
FIG. 8 is a diagram showing a desired relationship between the
volume of the spark plug chamber and the load on the engine.
Referring to the drawings, the internal combustion engine generally
designated 10 includes a water cooled block 11 having one or more
cylinders 12 each with a piston 13 mounted to reciprocate therein.
A water cooled head 14 is secured to the block 11 by conventional
means, not shown, and this head is provided with a domed recess 15
cooperating with the piston 13 and cylinder 12 to define a main
combustion chamber 16. A main intake valve 17 controls
communication between the main intake passage 18 and the main
combustion chamber 16. An exhaust valve, not shown, communicates
with the main chamber 16 to control flow of exhaust gases
therefrom.
An auxiliary combustion chamber 21 is defined with a thin wall
stainless steel cylindrical cup 22 secured within cavity 20
provided in the water cooled engine head 14. One end of this cup 22
has a hemispherical shape and the other end is open and is provided
with a terminal flange 23. A sleeve 24 connected by threads 25 to
the engine head 14 clamps the flange 23 between insulating washers
26 and 27 to secure the cup 22 in place. A first aperture 29 in the
cup forms a torch nozzle which establishes restricted communication
between the auxiliary combustion chamber 21 and the main combustion
chamber 16. A small clearance space 30 separates the cup 22 from
the walls of the cavity 20 and this space acts to insulate the cup
and minimize transfer of heat from the cup to the engine head
14.
A portion 32 of the lower end of the threaded sleeve 24 projects
into the open end of the cup 22, and this portion of the sleeve 24
carries a stationary seat 33. An auxiliary of third valve 34
includes a valve head 35 which closes against the seat 33. The
valve 34 controls intake of rich combustible mixture through the
passage 36 in the engine head 14 and through the interior passage
37 in the threaded sleeve 24. First and second carburetors (not
shown) supply rich mixture and lean mixture, respectively, through
throttle controlled passageways 38 and 39 connected to passages 36
and 18, respectively, all as shown in the copending application
identified above.
In accordance with the present invention, a chamber 41 for residual
gas is formed by wall 42 of the engine head 14. The cup 22 forms
one end of the chamber 41 and a second aperture 43 in the cup 22
establishes restricted communication between the chamber 41 and the
auxiliary combustion chamber 21. A conventional spark plug 45 is
connected by threads 46 to walls 42 of the engine head 14, and the
electrodes 47 are positioned within the chamber 41 to form a spark
gap which is located near the aperture 43 and remote from the end
wall 48.
Tests have shown that most desirable relationships between the
sizes of the chambers 41, 21 and 16, as well as the relationships
to the size of the apertures 29 and 43, are as follows: ##EQU1##
Where: V.sub.a = volume of auxiliary chamber 21
V.sub.rg = volume of residual gas chamber 41
V.sub.m = volume of main chamber 16 at top dead center
F.sub.t = area of torch nozzle aperture 29
F.sub.rg = area of restricted opening 43
In a commercial form of the invention as embodied in a
four-cylinder automobile engine of about 2,000 cc displacement, the
following volumes and sizes have produced very low NO.sub.x
emissions:
V.sub.a = 5.5 cc
V.sub.rg = 4.0 cc
F.sub.t = 0.5 sq. cm.
F.sub.rg = 0.5 sq. cm.
The exhaust valve (not shown), the main intake valve 17, and the
auxiliary valve 34 are opened and closed in timed sequence by
conventional cam mechanisms. At the end of the exhaust stroke of
the piston 13, residual gases remain in the main combustion chamber
16 and in the auxiliary chamber 21 and in the residual gas chamber
41. During the subsequent intake stroke of the piston, the main
intake valve 17 opens to admit a lean mixture into the main
combustion chamber, and the auxiliary valve 34 opens to admit a
rich mixture into the auxiliary chamber 21. The exhaust valve in
the main chamber closes. During the intake stroke of the piston,
very little change occurs in the chamber 41, but rich mixture fills
the auxiliary chamber 21 and is drawn through the torch nozzle 29
into the main chamber 16. Because of the shape of the main chamber
16, minimum turbulence is generated, and the rich mixture from the
auxiliary chamber 21 forms a region of relatively rich mixture
encompassed within a larger region of relatively lean mixture. In
other words, a stratified charge is formed in the main chamber 16.
Some residual exhaust gases remain dispersed in the main chamber
16.
During the following compression stroke of the piston 13, all of
the valves are closed and the increase in pressure in the main
chamber 16 causes reverse flow through the torch nozzle 29 so that
the mixture in the auxiliary chamber 21 is leaner than when
initially inducted, and so that the residual gas chamber 41
containing the spark plug electrodes then contains a compressed
mixture of air, fuel and residual exhaust gases. In the particular
2,000 cc displacement engine mentioned above, it has been found
that the residual gas percentage in each chamber at the end of the
compression stroke, as compared to the total amount of gas in each
chamber, is substantially as follows when the engine is operating
under partial load: Main chamber 16 12% Auxiliary chamber 21 14%
Spark plug chamber 41 20%
Accordingly, at the time of firing, the mixture in the spark plug
chamber 41 has a greater percentage of residual gas than either the
auxiliary chamber 21 or the main chamber 16. When the spark plug is
energized to produce a spark at the gap between the electrodes 47,
the peak temperature of the burning mixture is lower than it would
be if the residual exhaust gases were not present in the chamber
41. A first flame jet carrying both burning and residual gases is
projected through the aperture 43 to ignite the relatively small
quantity of rich mixture in the auxiliary chamber 21, producing
high turbulence. A second flame jet or torch is then projected
through the nozzle 29 to initiate burning of the stratified charge
and thereby ignite the large volume of relatively lean mixture
within the main combustion chamber 16.
The axis of the apertures 43 and 29 are purposely misaligned so
that (1) the first flame jet passing through the aperture 43 does
not also pass directly through the aperture 29, (2) the spark plug
electrodes are not fouled during the compression stroke by direct
infringement of a rich mixture jet, and (3) turbulence in the
residual gas chamber 41 is minimized during the compression stroke
to cause the main body of residual gas to be present under
compression adjacent said end wall 48.
After completion of the power stroke, the exhaust valve opens to
allow the exhaust gases to leave the engine, and they continue to
burn in the exhaust system downstream from the exhaust valve.
Because the overall air-fuel ratio is leaner than stoichiometric,
excess air is present in the exhaust system to burn any unburned
hydrocarbons and to oxidize the carbon monoxide to carbon dioxide
before discharge into the atmosphere.
The modified form of the invention shown in FIG. 2 uses the same
method of operation but the structure differs in that a sleeve 51
is employed in connection with a special spark plug 52 having
exceptionally long electrodes 53 and 54 forming a spark gap 55
between them. The space 56 within the sleeve 51 together with the
space within the bore 57 in the engine head 14a cooperate to form a
residual gas chamber generally designated 58. The sleeve 51 is
fixed to the engine head 14a by threads 59, and the spark plug 52
is fixed to the sleeve 51 by threads 60. The spark gap 55 is
positioned in the chamber 58 close to the aperture 43a and remote
from the rear wall 61. The axis of the aperture 43a in the cup 22a
is misaligned from the axis of the torch nozzle 29a. The operation
of this form of the invention is similar to that described above.
This modification, however, has the advantage that the type of
threevalve stratified charge engine disclosed in the copending
application referred to above may be directly converted to use the
principles of this invention for further reduction of NO.sub.x
emissions, by simply replacing the standard spark plugs with the
special spark plugs 52 and the sleeves 51.
The modified form of the invention shown in FIG. 3 is similar to
that shown in FIG. 1, but with the additional feature that a thin
wall stainless steel liner 65 is placed within a cavity 66 formed
in the engine head 14b. A small clearance space 67 between the
liner 65 and the walls of the engine head 14b serves to insulate
the liner and minimize transfer of heat from the liner to the
engine head. The liner 65 is held in proper position within the
cavity 67 by means of a circular disk 68 spot welded at 72 to the
end wall of the liner 65. This disk 68 is clamped against a
shoulder 69 by means of a plug 70 connected to the walls of the
engine head 14b by threads 71.
A conventional spark plug 73 is connected by threads 74 to the head
14a and the spark plug electrodes 74 are positioned within the
residual gas chamber 75. A portion of the spark plug including the
electrodes 74, and a portion of the wall 76 of the head 14b both
project through a lateral opening 77 in the wall of the liner 65.
The proportions of the parts are such that, in the absence of the
spark plug 73 and the closure plug 70, the liner 65 with its
centering disk 68 may be moved through a curved path to accomplish
installation within the cavity 66, and to bring the opening 77 into
position to encompass a projecting portion 76 of the wall of the
engine head 14b.
The operation of this form of the invention is the same as that
described in connection with FIG. 1, except that the thin wall
stainless steel liner 65 heats up rapidly under initial startup
conditions and stays hot during operation of the engine. This has a
beneficial effect on engine performance.
The form of the invention shown in FIGS. 4-7 includes a residual
gas chamber which has a volume which may be increased or decreased
as desired, during the operation of the engine. The exhaust gas
chamber 81 contains the spark plug electrodes 82 and the chamber
communicates with the auxiliary chamber 21c through the aperture
43c as previously described. However, a sliding end wall or plug 83
is received within the bore 84 in the walls of the engine head 14c,
and this plug is movable between the advanced position shown in
FIG. 4 and the retracted position shown in FIG. 6. Accordingly, the
minimum dimensions of the residual gas chamber 81 are shown in FIG.
4, while the maximum dimensions are shown in FIG. 6. Means are
provided for adjusting the position of the sliding plug 83 within
the bore 84, and as shown in the drawings this means includes a
cylindrical member 85 fixed to the plug 83 in offset eccentric
position and carrying a pair of radially projecting pins 86. Each
pin is received in a helical groove 87 provided in a rotary
actuator sleeve 88 mounted concentrically with the member 85. The
actuator sleeve 88 may be turned through a portion of one
revolution by means of a crank arm 89 fixed to a projecting end of
the sleeve. A retainer plate 90 is secured to the engine head 14c
by means of threaded fastenings 91. From this description it will
be understood that turning of the actuator sleeve 88 by means of
the crank arm 89 serves to advance or retract the sliding plug 83
to vary the volume of the residual gas chamber 81.
The graph shown in FIG. 8 shows that it is desirable to vary the
volume of the residual gas chamber in accordance with variations of
load on the engine. In many cases it may be desirable to increase
the chamber volume continuously with increasing load on the engine,
as shown by the graph. This may be accomplished by connecting the
control rod 95 for the arm 89 to either the accelerator pedal 96 or
to the pressure sensitive mechanism 97 which is operated by vacuum
in the intake manifold of the engine.
Having fully described our invention, it is to be understood that
we are not to be limited by the details herein set forth but that
our invention is of the full scope of the appended claims.
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